Sleep as much as you can, because pretty soon you won't be sleeping hardly at all.
Just kidding, but you probably will find yourself sleeping a little less than you have been once you start.
I'm in my last semester of paramedic school, so I'll give you what was probably the best advice that was given to me by my program director. In paramedic school, you'll find yourself struggling at first, and then you'll finally reach a point where you've gotten the hang of it and you plateau and you'll start to feel comfortable, and then you'll have to start climbing again. And then you'll reach another plateau, and you'll get comfortable, but it won't last for very long before you find yourself climbing yet again. Every time you reach that plateau and you get to where you feel like you've got the hang of it, you're going to find yourself having to climb and work a little bit more. That's how it has been for me throughout the entire program, anyway.
It's a lot of fun, and if you really want it you're going to find yourself loving every minute of it--even when you're sick to death of it at the same time. It's worth every second, every bead of sweat, and every moment of thinking "I'm never going to get this." Another piece of advice, for the love of everything holy, have your social and family life in order, and definitely have your finances in order. Day one of field internship is not the time to realize that you aren't going to be able to keep a roof over your head unless you can keep working full time at your day job--and trust me, you won't have time for that in field internship.